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Problem C
R2
The number $S$ is called the mean of two numbers $R_1$ and $R_2$ if $S$ is equal to $(R_1+R_2)/2$. Mirko’s birthday present for Slavko was two integers $R_1$ and $R_2$. Slavko promptly calculated their mean which also happened to be an integer but then lost $R_2$! Help Slavko restore $R_2$.
Input
The first and only line of input contains two integers $R_1$ and $S$, both between $-1\, 000$ and $1\, 000$.
Output
Output $R_2$ on a single line.
| Sample Input 1 | Sample Output 1 |
|---|---|
11 15 |
19 |
| Sample Input 2 | Sample Output 2 |
|---|---|
4 3 |
2 |